Prior art patent document published WO 2015/132092 A2 discloses a gas cylinder with a tap and a tap cover comprising a shell for housing the tap and a hook pivotally mounted on the shell. The hook is configured for securing the gas cylinder in an upright position to a horizontal bar of a hospital bed. The shell comprises reservations on its external surface configured for receiving the hook in a folded position so as to generally conform to said external surface. The use of a cover with a handle is interesting in that it provides an ergonomic protection for the tap that fulfils additional functions such as providing a handle, providing a convenient rotating flow selector and providing a hook for securing the cylinder to a bar like a bar of a hospital bed. That document is however silent about any indication of the pressure in the gas cylinder and/or the remaining service time.
Prior art patent document published WO 2014/074313 A1 discloses a tap for gas cylinders, that provides a function of indicating the amount of gas left in the cylinder. To that end, the tap comprises a pressure sensor, an electronic display and an electronic control system electrically connected to the pressure sensor and the display. The control system is configured for calculating an operation time that is left until the amount of gas in the cylinder reaches a predetermined low level. This calculated time is displayed with the electronic display. The electronic control system is supplied in electrical energy by a battery. This system is either affixed to the tap or to a protective cap. When affixed to the tap, the system comprises a pressure sensor that is fluidly connected to the tap via the mounting of said system to the tap body. The system comprises also switching means for detecting the angular position of a flow selector located at the top of the tap. The teaching is quite interesting by the functions that the tap can fulfil. The modularity is however limited in that the control system, the pressure sensor and the display are housed in a common housing forming an electronic manometer. Also, the integration of the pressure sensor, the electronic display, the electronic control system and the battery remains however subject to improvements.